(1) Field of the Invention
This invention relates to a magnetic separator for magnetically separating finely divided powder ores, etc. into magnetic components and non-magnetic components.
(2) Description of the Prior Art
There have conventionally been proposed a variety of apparatuses for magnetically separating ores into magnetic components and non-magnetic components using permanent magnets or magnetic poles consisting of electromagnets. However, these heretofore known apparatuses involve the drawback in their method of separating the ores in that they have a large and complicated construction and are not entirely satisfactory with respect to the separation accuracy and with regard to rate of production.
In carrying out the magnetic ore separation, the most critical problem is that when magnetic particles are magnetized by magnetic induction, the magnetic particles attract one another and entrap non-magnetic particles between them, thus prohibiting the perfect and satisfactory magnetic separation. This phenomenon is usually referred to as "entrapping" or "entraining" and is enhanced remarkably as the particles are smaller, thereby lowering the ore separation efficiency.
In order to solve this problem, the conventional apparatus includes separate devices as external means for floating the ore material to be separated by an air pressure, for forming a fluidized layer, for generating an air jet and the like in addition to the separation means using magnetic poles, for the purpose of dispersing and floating the ore simultaneously with, or during, the magnetic separation. However, when the ore for the separation is brought into the dispersed and floating state by such external means, the particles are, on the contrary scattered whereby the magnetic particles can hardly be collected onto the magnetic poles in an effective manner. In order to efficiently collect the dispersed and floating particles, therefore, it is necessary to use strong magnetic poles or a large and complicated mechanism for generating a strong magnetic force, which inevitably results in a drastic increase in the cost of installation and the running cost of the system.
Among the prior art references collected by the applicant of the present invention, U.S. Pat. No. 2,437,681 to R. E. Crockett, et al. discloses an apparatus for the magnetic separation of ores which recovers the concentrate (magnetic component) into an upper trough by the action of series of stationary magnetic poles aligned along one surface of an upwardly running conveyor belt while the feed material for the separation is being conveyed by the conveyor belt.
In U.S. Pat. No. 3,289,836 to D. Weston, the feed material for the magnetic separation moves along the feed pathway concurrently to the movement of moving magnets whereby only the concentrate is recovered in a concentrate chute together with the moving magnets and the tailing (non-magnetic component), which is not brought under the influence of the magnetic field, falls and is thus collected. In this patent too it is practically impossible to improve the ore separation efficiency unless a fluid is jetted into the apparatus so as to agitate slimes which tend to build up on the walls of the rotary drum.
The present invention contemplates providing a satisfactory solution to these drawbacks of the prior art.